1. Field of the Invention
The invention relates to lasers, and, more particularly, to the use of single crystal chromium-doped beryllium aluminate in laser applications.
2. Description of the Prior Art
The use of lasers in science and industry has received wide acceptance in an ever increasing variety of applications. Lasers have found use in such diverse areas as range finding apparatus, optical surgery and metal drilling. Briefly, lasers operate on the principle of light amplification through stimulated emission of radiation and can create extremely intense concentrations of light. The coherent light beam produced in a laser cavity is amplified in a laser host material. Materials which have been used as laser hosts include gases, liquids, glasses and single crystalline solids.
When single crystalline solids are utilized in lasers, the crystals are generally in the form of elongated rods. The structure of the crystalline material must be very nearly perfect, since any optical inhomogeneities will cause distortion and scattering of the laser beam and thereby reduce the intensity and coherence of the radiation. Imperfections in the crystal which adversely affect lasing performance include elastic strain, crystal misorientations, chemical concentration inhomogeneities, dislocations, inclusions and bubbles.
The first room temperature laser, disclosed several years ago, utilized Al.sub.2 O.sub.3 :Cr.sup.3+ (ruby). In more recent developments, room temperature lasers have been fabricated from rare earth ion-doped materials. Examples include Y.sub.3 Al.sub.5 O.sub.12 :Nd.sup.3+ (YAG:Nd) and Y.sub.2 Al.sub.2 O.sub.6 :Nd.sup.3+ (YALO:Nd).
Attempts have been made to synthesize other Cr.sup.3+ -doped materials for laser applications. For example, the growth of single crystal chromium-doped beryllium aluminate (BeAl.sub.2 O.sub.4 :Cr.sup.3+) for possible use as a laser host has been disclosed by R. C. Linares in "Research and Development of New Laser Materials" in a report to the Air Force Cambridge Research Laboratories, AD-611177 (AFCRL-64-971), dated Oct. 30, 1964. It was found, however, that this material did not exhibit lasing action. While other chromium-doped materials, such as Y.sub.3 Al.sub.5 O.sub.12 :Cr.sup.3+, have evidenced lasing at low temperatures such as 77.degree. K., nevertheless, with the exception of ruby, no chromium-doped materials have heretofore been successfully used as room temperature laser hosts.